Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description meaningfully extends this by disclosing cost ('Cost: free'), authentication requirements ('unauthenticated'), the structured JSON return shape, and API-wide spend headers. This goes well beyond the annotations and gives agents clear expectations for cost, auth, and response behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the main deliverable and packs useful details about output contents, use cases, auth, and headers. It is slightly longer than strictly necessary and repeats the 'free' point ('Free and unauthenticated' and 'Cost: free'), but every clause otherwise earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter, read-only tool with rich annotations, this description is highly complete. It specifies the full output catalog, the pricing and auth context, and the response-header behavior relevant to resellers. Even without an output schema, an agent has enough context to invoke the tool and interpret its result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has zero parameters, so the baseline is 4. The description adds no parameter details, but none are needed. It effectively explains the result of calling the tool with no inputs.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('Returns the current price list as structured JSON') and enumerates the exact contents: credit value, skill costs/routes, credit packs, subscription plans, and watchlist limits. This clearly differentiates it from related sibling tools like get_credit_balance, which focuses on the current balance rather than the full pricing catalog.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear use cases: integrators rendering live costs, agents comparing subscriptions vs packs, and resellers attributing spend. It also states the tool is free and unauthenticated, implying when it can be used without credentials. However, it does not explicitly name sibling alternatives or say when not to use this tool, so it stops short of a full when/when-not comparison.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.